<meta name="viewport" content="width=device-width,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no">

<img src="pic_bulboff.gif" onclick="kaiGuan()" id="deng" />

<script>
    var i = 1;

    function kaiGuan(){
        if(i==1) {
            deng.src = "pic_bulbon.gif";
            i = 0;
        }else{
            deng.src = "pic_bulboff.gif";
            i = 1;
        }
    }
</script>